In the wake of last year’s devastating Tohoku earthquake and tsunami, the Tokyo metropolitan government has revised its own disaster scenarios for the first time in six years. The chilling result: As many as 9,700 people could die if a big earthquake were to strike near the capital.

That projection is for one of four earthquake scenarios prepared by a Tokyo government panel of earthquake experts, in a 400-page report released Wednesday. It assumes a Magnitude 7.3 earthquake centered in the Tokyo Bay hits at 6 p.m. on a winter evening, with winds blowing at a speed of eight meters per second. The casualty rate is more than 3,000 people higher than estimated in a similar scenario in Tokyo’s 2006 report.

About 57% of those deaths would result from earthquake damage and the rest from fires, which would be spread across the city’s 23 wards, the report says. The earthquake could be followed by a tsunami that reaches a maximum of 2.6 meters (8.5 feet) in Shinagawa ward, a district of southeastern Tokyo that borders the bay. About 300,000 buildings would be completely destroyed, many burnt to the ground. Meanwhile, 147,600 would be injured and 5.16 million people would be stranded and unable to go home, the report says.

The other disaster scenarios included one that imagined what would happen if the Magnitude 8.2 Genroku earthquake — which killed 2,300 and triggered a major tsunami that claimed another 6,500 lives in 1703 — struck today (the report estimates only 5,900 deaths, since Genroku hit offshore further south than the Tokyo Bay). It also estimated the damage if a Magnitude 7.4 earthquake hit at the Tachikawa fault line in western Tokyo (2,600 projected dead).

All the scenarios in the current report — like other post-March 11 re-evaluations — assume more severe disaster conditions than previous reports had. This time, all the earthquake scenarios exceeded a seismic intensity of 7, while in 2006 one scenario only assumed a magnitude of 6.9. The higher threshold seems appropriate, since research conducted by the Tokyo University Earthquake Research Institute earlier this year said there was a 70% probability the capital will face a Magnitude 7 or bigger earthquake by 2016. The forecast has since been revised downward to about a 50% chance within the four years.

Last year’s March 11 Magnitude 9 earthquake and tsunami claimed more than 19,000 lives.

The latest Tokyo government report also factors in the recent discovery that the tectonic plates beneath Tokyo are shallower than previously thought.

The Tokyo government will begin to formulate revised disaster preparedness plans in September, based on this latest report.

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